Hybrid seismic enclosure using cross laminated timber and high pressure laminate

Abstract

The present invention relates to a hybrid seismic enclosure combining a metal frame and engineered wood to achieve carbon dioxide emission reduction and maximize seismic performance. The enclosure according to the present invention has a structure in which a metal vertical bar with embedded Cross Laminated Timber (CLT) and an HPL (High Pressure Laminate) exterior panel are combined on the upper part of a steel base frame. In particular, by interposing HPL vibration damping foundation units with a multi-layer laminated structure at the vertical load support points and the bottom of the horizontal bar, seismic energy is structurally blocked and dissipated through the impedance difference between dissimilar materials and the viscoelastic damping of the HPL. This ensures eco-friendliness while safely protecting internal power equipment from external impacts.

Description

Technology Field

[0001] The present invention relates to an enclosure for a switchboard or control panel, and more specifically, to a hybrid seismic-resistant switchboard enclosure that achieves carbon dioxide reduction by combining structural laminated timber (CLT) and high-density wood panels (HPL) with a metal frame, while simultaneously structurally blocking and absorbing the transmission of seismic wave energy by utilizing the difference in damping coefficients between dissimilar materials. Background Technology

[0002] Generally, switchgear is power equipment that converts and distributes high-voltage electricity to a voltage usable by consumers, and it is equipped with heavy components such as transformers, circuit breakers, and instrument transformers.

[0003] Conventional enclosures for switchboards and control panels, as disclosed in Korean Registered Patent No. 1637181, were manufactured primarily by welding or bolt-assembling general structural rolled steel (such as SS400). While steel is suitable for supporting heavy loads due to its excellent tensile strength and stiffness, it presents a problem in that its high elastic modulus transmits ground vibration energy to internal equipment without attenuation during an earthquake.

[0004] In other words, if a steel enclosure resonates with the frequency band of seismic waves, the vibration acceleration is amplified, posing a high risk of damaging internal precision contact points or insulators. To address this, a seismic isolation device with a separate coil spring or oil damper installed at the bottom has been proposed, but this has the disadvantage of a complex structure, increased installation height, and higher costs.

[0005] Furthermore, driven by the global trend toward carbon neutrality, there is a growing demand to reduce carbon dioxide emissions generated during the manufacturing phase of industrial equipment. While steel emits massive amounts of carbon dioxide during production, attempts to apply eco-friendly materials with comparable structural strength to switchboards have not been commercialized due to technical limitations, such as wood's poor fire resistance, warping caused by moisture, and insufficient strength.

[0006] Therefore, there is an urgent need to develop a new type of switchgear enclosure that can absorb seismic energy and drastically reduce carbon dioxide emissions through the material properties itself, while maintaining structural rigidity at the level of existing steel frames. The problem to be solved

[0007] The present invention was devised to solve the problems of the aforementioned conventional technology. First, it aims to achieve a specific strength equivalent to that of reinforced concrete while reducing carbon dioxide emissions by reducing steel usage, by inserting cross-laminated timber (CLT) into the longitudinal bars forming the rectangular frame that serves as the skeleton of the rectangular enclosure, joining them to the base frame, and constructing the outer shell with high-density wood panels (HPL).

[0008] Second, the purpose is to maximize seismic performance by utilizing a hybrid structure that uses the different natural frequencies and damping characteristics of metal and wood materials, allowing the enclosure itself to absorb and scatter seismic vibrations without the need for separate, expensive seismic isolation devices.

[0009] Third, by laminating HPL material compressed at high temperature and high pressure and interposing it between the base frame and the horizontal bar of the rectangular frame, the purpose is to primarily filter the impact load transmitted from the ground and structurally compensate for the disadvantages of wood, such as moisture penetration and fire vulnerability. means of solving the problem

[0010] A hybrid seismic enclosure according to an embodiment of the present invention for solving the above problem comprises: a base frame formed of a metal material and fixed to the ground; a rectangular frame made of a metal material mounted on the upper surface of the base frame; four vertical columns extending in a vertical direction and inserted and fixed into four vertical bars forming the rectangular frame, and composed of structural laminated timber (CLT) in which a plurality of wood layers are laminated to have grains in intersecting directions; a floor exterior panel made of high-density wood panel (HPL) material interposed between the vertical columns and the base frame; a corner vibration damping foundation unit interposed between the bottom surface of the four vertical columns and the floor exterior panel, formed by multi-layering of high-density wood pieces (HPL); and a lower horizontal side vibration damping foundation unit interposed between four lower horizontal bars forming the rectangular frame and the floor exterior panel, formed by multi-layering of high-density wood pieces (HPL). and includes an exposed exterior panel made of high-density wood panel (HPL) material that is joined to wrap around the outer surface of the rectangular frame. Effects of the invention

[0011] According to the present invention, first, by configuring the columns of the enclosure with CLT and metal vertical bars of a rectangular frame, and the outer casing with HPL, the weight can be drastically reduced compared to a general steel enclosure, and an eco-friendly effect of reducing carbon dioxide emissions during the manufacturing process and storing carbon can be obtained.

[0012] Second, by hybridizing wood materials, which have superior damping capabilities compared to steel, with metal materials, which possess excellent rigidity, it exhibits a self-damping effect that dissipates vibrational energy into thermal energy through internal friction and viscoelastic properties during an earthquake.

[0013] Third, the foundation unit with a multilayer HPL structure acts as an isolator that blocks high-frequency vibrations between the base frame and the vertical columns, and between the base frame and the rectangular metal crossbars, thereby protecting the internal power equipment.

[0014] Fourth, due to the unique chemical resistance and corrosion resistance of CLT and HPL materials, corrosion does not occur even in environments with high humidity or salt, which can extend the lifespan. Brief explanation of the drawing

[0015] FIG. 1 is an overall perspective view of a hybrid seismic enclosure according to one embodiment of the present invention. Figure 2 is an exploded perspective view with the exterior panel separated to show the main skeletal structure of Figure 1. FIG. 3 is a perspective view illustrating the connection between the base frame and the bracket and the connection between the bracket and the rectangular frame of FIG. 1. FIG. 4 is a partial cross-sectional detail view illustrating the combined relationship between the floor exterior panel, the vibration damping foundation unit (HPL), and the base frame, which are the core components of the present invention. FIG. 5 is a front view of FIG. 1, FIG. 6 is an enlarged view of section 'A' of FIG. 5, and Figure 7 is a cross-sectional view of line BB of Figure 5. Specific details for implementing the invention

[0016] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0017] A hybrid seismic enclosure (100) according to one embodiment of the present invention comprises, as shown in FIGS. 1 to 7, a base frame (110) formed of a metal material and fixed to the ground (concrete) by anchor bolts (111); a rectangular frame (120) made of a metal material mounted on the upper surface of the frame (110); four vertical columns (130) made of structural laminated wood (CLT) that are inserted and fixed into four vertical bars (121) among the bars forming the rectangular frame (120) extending in a vertical direction, and having a plurality of wood layers laminated to have a grain in a direction intersecting each other; and a floor exterior panel (140) made of high-density wood panel (HPL) material interposed between the four vertical columns (130) and the base frame (110). It includes: a corner vibration damping foundation unit (150) interposed between the bottom surface of the four vertical columns (130) and the floor exterior panel (140), formed by stacking high-density wood pieces (HPL) in multiple layers; a lower horizontal vibration damping foundation unit (160) interposed between the four lower horizontal bars (122) forming the rectangular frame (120) and the floor exterior panel (140), formed by stacking high-density wood pieces (HPL) in multiple layers; and an exposed exterior panel (170) made of high-density wood panel (HPL) material coupled to the vertical columns (130) to surround the ceiling and wall portions of the rectangular frame (120).

[0018] The vertical column (130) is inserted into the vertical bar (121) to integrate the rigidity of the metal and the damping performance of the wood. The structural laminated timber (CLT) material has wood layers stacked orthogonally, so it has significantly improved resistance compared to ordinary wood not only to vertical compressive loads but also to horizontal shear loads during earthquakes. In particular, the wood used for the vertical column (130) absorbs carbon dioxide from the atmosphere during the growth process and fixes it in the form of carbon within the structure, thereby reducing the amount of steel used during the construction of the enclosure, thereby suppressing carbon dioxide generation, while simultaneously providing the effect of semi-permanently storing carbon inside the enclosure.

[0019] In contrast to this configuration, conventionally, all frames were made of steel, which had the problem of ground vibrations being transmitted to internal equipment without damping. This is because steel lacks the ability to dissipate energy in the elastic region, so acceleration is amplified when resonance occurs. In order to solve this problem, the present invention blocks the vibration transmission path by arranging foundation units (150, 160) of a multilayer HPL structure as part of the idea that an impedance mismatch design due to differences in elastic modulus and density between materials can be introduced.

[0020] The above base frame (110) is positioned such that an open portion with a channel cross-sectional shape is placed on the outside, and the ends of bars having a channel cross-sectional shape are joined together to form a rectangle, and is fixed to the ground by an anchor bolt (111).

[0021] The above rectangular frame (120) is formed by combining the ends of four vertical bars (121) that have a P-shaped cross section and are extended in the vertical direction, with through holes formed at intervals along the length of the walls in four walls facing each other in the horizontal direction; and eight horizontal bars (122) that have an angle cross section and are extended in the horizontal direction, with through holes formed at intervals along the length of the walls in two walls facing each other in the vertical direction.

[0022] In addition, the lower ends of the four vertical bars (121) protrude further downward than the lower horizontal bar (122) so that the lower horizontal bar (122) separates from the floor exterior panel (140) to form a ventilation passage, and act as legs.

[0023] Each of the four vertical columns (130) is connected to the vertical bar (121) by driving an unillustrated piece through a through hole formed in the four walls of the vertical bar (121) while the vertical bar (121) is inserted along the longitudinal direction of the vertical bar (121).

[0024] That is, the vertical bar (121) has a P-shaped cross-sectional structure extended in the vertical direction, forming a hollow portion that accommodates the vertical column (130) inside, and the vertical column (130) is shaped and integrated into the internal space of the vertical bar (121).

[0025] Each of the four vertical columns (130) comprises: a bracket (180) that is fixed to the vertical column (130) by an unillustrated piece, having the shape of a rectangular metal box with a closed bottom, so as to be externally in contact with the four wall portions of the vertical column (130) and internally in contact with the four wall portions of the vertical bar (121) in order to be joined to the base frame (110) and the floor exterior panel (140); and a column bolt portion (181) that has its upper end fixed by means such as welding and its lower end extending vertically downward at the center of the bottom surface of the rectangular bracket (180).

[0026] The corner vibration monitoring foundation unit (150) has a through hole formed in the center that is externally contacted with the column bolt part (181).

[0027] Accordingly, each of the four vertical columns (130) is connected to the base frame (110) and the floor exterior panel (140) by attaching the corner vibration monitoring foundation unit (150) to the column bolt portion (181), and sequentially passing the column bolt portion (181) through the floor exterior panel (140) and the base frame (110) in a state where a bolt through hole is formed in the part facing the column bolt portion (181), and then fastening the column nut portion (182) to the exposed column bolt portion (181) portion in the base frame (110).

[0028] In each of the above lower horizontal vibration damping foundation units (160), through holes are formed at intervals along the length direction of the corresponding lower horizontal bar (122).

[0029] Accordingly, each of the four lower crossbars (122) is connected to the base frame (110) and the base frame (140) by inserting the lower crossbar vibration damping foundation unit (160) between the lower crossbar (122) and the floor exterior panel (140) facing it, and sequentially penetrating the lower crossbar vibration damping foundation unit (160), the floor exterior panel (140), and the base frame (110) facing the crossbar bolt part (183), and then fastening the crossbar nut part (184) to the crossbar bolt part (183) exposed in the base frame (110).

[0030] The exposed exterior panel (170) corresponding to the ceiling portion of the rectangular frame (120) is fixed to the upper surface of the facing vertical column (130) and the upper surface of the four upper horizontal bars (122) by pieces not shown, and the exposed exterior panel (170) corresponding to the four wall portions of the rectangular frame (120) is fixed to horizontal bolts (171) and horizontal nuts (174) penetrating the facing vertical bar (121) and the vertical column (130) and to the vertical surface of the eight horizontal bars (122) by pieces not shown.

[0031] The base frame (110) is a foundation structure that is firmly fixed to the ground or the floor of a building through anchor bolts, etc., and is typically made of general structural rolled steel (e.g., SS275, SS400, etc.) or stainless steel having high rigidity. It serves to support the load of the entire enclosure and receive primary external forces transmitted from the ground.

[0032] The above corner vibration damping foundation unit (150) is interposed between the base frame (110) and the vertical column (130) described later, together with a floor exterior panel (140) made of high-density wood panel (HPL), and is formed by laminating multiple layers of high-density wood panel (High Pressure Laminate, HPL). This HPL is a material produced by impregnating dozens of sheets of kraft paper with phenolic resin and then compressing them at high temperature and high pressure. It has a Mohs hardness of 5 to 6, possessing surface strength comparable to steel, while retaining a unique viscoelasticity different from metal.

[0033] The above-mentioned vertical structural column (130) is a core member that forms the frame of the enclosure together with a metal rectangular frame (120), and is made of structural cross-laminated timber (CLT). This CLT is engineered wood formed by cross-lamining sawn wood layers in orthogonal directions and bonding them together. As the fiber directions of the wood intersect at 90 degrees, dimensional deformation caused by shrinkage and expansion, which are inherent disadvantages of wood, is suppressed, and resistance to shear force and compressive force is dramatically improved.

[0034] The floor exterior panel (140) and the exposed exterior panel (170) constitute the outer surface of the vertical column (130), namely the door, side panel, top panel, and bottom panel of the enclosure, and are made of the same high-density wood panel (HPL) material as the vibration damping foundation unit (150, 160).

[0035] In contrast to this configuration, conventional enclosures for switchboards or control panels consisted entirely of metal (steel), from the base to the columns and outer casing. Since steel is close to a perfectly elastic material, its damping ratio is very low, ranging from 0.01 to 0.02. Consequently, there was a critical problem in which, during an earthquake, the vibrational energy of the ground could not be dissipated as thermal energy, and the entire enclosure resonated with the seismic waves to transmit amplified vibrations to the internal equipment. Furthermore, steel has a high thermal conductivity, which easily transfers external heat to the interior, causing overheating of the equipment or condensation, which can lead to electrical short-circuit accidents.

[0036] In order to solve these conventional problems, the present invention attempts a paradigm shift by applying CLT, which has a higher specific strength than concrete, and metal vertical bars to the frame where structural rigidity is required, and introducing a multilayer HPL structure with excellent shock absorption capabilities to the connection points where shock and vibration are concentrated. In particular, by sequentially combining a steel base frame (110), an HPL foundation (150, 160), and a CLT vertical column (130) having different physical properties (density, elastic modulus), a structure is adopted that significantly reduces the vibration transmissibility by inducing reflection and scattering effects due to impedance mismatch whenever seismic waves pass through the boundary surface of each medium.

[0037] Here, it is necessary to pay attention to the physical properties of the CLT applied to the vertical column (130). Since the fiber direction of the wood in CLT is orthogonal to each layer, the wood's tendency to split in a specific direction (anisotropy) is offset, resulting in structural stability close to isotropy. This allows the steel frame to withstand a shear load applied horizontally during an earthquake by dispersing the stress across the entire surface area, whereas the CLT column exhibits a 'shear wall' effect.

[0038] In addition, the cellular structure within the wood acts as a friction damper that absorbs vibration energy. In fact, the specific strength (strength relative to density) of CLT is about nine times that of concrete and about twice that of steel, so it is possible to significantly reduce the self-weight of enclosures for switchboards or control panels (one-fifth the weight of reinforced concrete) while still ensuring sufficient structural strength.

[0039] The above vibration damping foundation unit (150, 160)) preferably has a laminated structure in which multiple HPL panels are stacked, rather than a single panel.

[0040] The above vibration damping foundation unit (150, 160) is positioned between the base frame (110) and the vertical structural column (130) and exhibits behavior similar to a 'leaf spring'. Shock waves of high-frequency components traveling up the steel base frame (110) are damped at the interface between the HPL layers. Since HPL is a laminate of kraft paper impregnated with phenolic resin, unlike metal, it has numerous layered structures inside, which lengthens the vibration transmission path and dissipates energy.

[0041] HPL used as an exterior panel (140, 170) may have lower tensile strength compared to general steel plates (SS400), but it has excellent resilience. When an object collides with it from the outside or a torsional moment occurs due to an earthquake, steel plates are prone to plastic deformation (permanent denting), whereas HPL has a strong property of bending within the elastic range and then restoring to its original shape. This means it has excellent 'dent resistance' and provides excellent effects in maintaining the external shape and internal airtightness of the enclosure for switchboards or control panels. In addition, the anti-contamination and chemical resistance of the HPL surface serve to permanently protect the enclosure from acid rain or salt damage when installed outdoors.

[0042] Furthermore, the significance of the present invention is clear from the perspective of carbon neutrality. The wood used in the vertical structural column (130) is a carbon reservoir that absorbs and stores carbon dioxide during the growth process. Just as a wooden building of 63 m² stores approximately 34.6 tons of carbon, every time one side of an enclosure for a switchboard or control panel is manufactured according to the present invention, not only is the amount of carbon dioxide emissions generated when manufacturing an equivalent steel enclosure reduced, but the effect of fixing carbon inside the wood is also obtained. This constitutes a powerful industrial advantage that can respond to environmental regulations such as the carbon emission trading system.

[0043] Although the present invention has been described with reference to specific embodiments in the above description, the present invention is not limited thereto. For example, the number of stacked vibration damping foundation units (150, 160) can be adjusted according to the seismic zone coefficient of the installation area, and the thickness of the vertical structural columns (130) can also be optimized through structural calculations according to the weight of the power equipment housed therein. All such variations are included within the scope of the technical concept of the present invention.

[0044] Furthermore, due to the unique chemical and corrosion resistance of CLT and HPL materials, corrosion does not occur even in environments with high humidity or salt, thereby extending the lifespan of the enclosure. Additionally, if the eco-friendly cooling structure presented in the applicant's pending patent application No. 10-2025-0117486 is applied to the enclosure, it is desirable in that it can protect the electrical equipment inside the enclosure from moisture. Explanation of the symbols

[0045] 100: Enclosure, 110: Base frame, 111: Anchor bolt, 120: Rectangular frame, 121: Vertical bar, 122: Horizontal bar, 130: Vertical column, 140: Floor exterior panel, 150: Corner vibration damping foundation unit, 160: Lower horizontal side vibration damping foundation unit, 170: Exposed exterior panel, 171: Horizontal bolt, 174: Horizontal nut, 180: Bracket, 181: Bolt section for column, 182: Nut section for column, 183: Bolt section for horizontal bar, 184: Nut section for horizontal bar

Claims

Claim 1 A base frame (110) fixed to the ground and formed of a metal material; a rectangular frame (120) made of a metal material mounted on the upper surface of the base frame (110); four vertical columns (130) formed of structural laminated wood (CLT) that extends vertically and is inserted and combined within four vertical bars (121) forming the rectangular frame (120), wherein multiple wood layers are cross-laminated to have grains in mutually orthogonal directions, and dissipates seismic vibration energy into thermal energy through the viscoelasticity of the CLT material having a damping coefficient different from that of the metal material; a floor exterior panel (140) made of high-density wood panel (HPL) material interposed between the vertical columns (130) and the base frame (110); and a high-density wood panel (HPL) sheet interposed between the bottom surface of the vertical columns (130) and the floor exterior panel (140), formed by stacking multiple layers of the high-density wood panel (HPL), and the base frame (110) and the vertical Corner vibration damping foundation unit (150) that blocks high-frequency vibrations by reflecting and scattering seismic waves due to impedance mismatch between different materials between columns (130); lower horizontal vibration damping foundation unit (160) that is interposed between four lower horizontal bars (122) forming the rectangular frame (120) and the floor exterior panel (140), is formed by stacking high-density wood panels (HPL) in multiple layers, and filters impact loads transmitted from the ground due to impedance mismatch between different materials;A hybrid seismic enclosure comprising an exterior panel (170) made of high-density wood panel (HPL) material that is combined to wrap around the outer surface of the corresponding rectangular frame (120), wherein the base frame (110), the corner vibration damping foundation unit (150), the lower horizontal vibration damping foundation unit (160), and the vertical column (130) are sequentially arranged in heterogeneous materials having different elastic moduli and densities, thereby reducing the vibration transmission rate by inducing reflection and scattering effects due to impedance mismatch whenever a seismic wave passes through the boundary surface of each material. Claim 2 A hybrid seismic enclosure according to claim 1, wherein a metal bracket (180) formed to wrap around the bottom surface and a portion of the four sides of the vertical column (130) is provided at the bottom of the vertical column (130), and a column bolt portion (181) is formed on the bottom surface of the bracket (180) to protrude downward and vertically penetrate the corner vibration damping foundation unit (150), floor exterior panel (140), and base frame (110) to be fastened with a nut. Claim 3 A hybrid seismic enclosure according to claim 1, wherein the vertical bar (121) has a P-shaped cross-sectional structure extending in the vertical direction, forming a hollow portion that accommodates the vertical column (130) inside, and the vertical column (130) is integrally formed by being shaped-joined to the internal space of the vertical bar (121).

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